monthly in daily

[Celine Bonfils <celine@xxxxxxxxxxxxxxxxxxxxxxxxxx>]

Hi Ferret users,

I have got 2 variables for one year: the absorbed solar radation at the 
surface (ASR) and the solar insolation at the top of the atmosphere (INSOL).
Both share the same spatial grid (lon,lat) but ASR is in daily ouptput (t=365) 
and INSOL is in monthly output (t=12). Since the seasonal cycle of INSOL is very 
regular, I would like to extrapolate INSOL to get it in daily resolution.
Then, I would be able to compute the ratio between the 2 variables in daily 
data.

I tried different ways to regrid INSOL on the grid of ASR but without success
(e.g.: on a graph which has a time-axis ranged between 1 and 365, I can 
plot the seasonal cycle of INSOL between t=1 and t=12, but not between t=1 and 
t=365). Finally, I am wondering if ferret can do that...
Maybe someone could help!

Thank you very much,
Celine